Evaporative coolers

ABSTRACT

A method of and installation for evaporatively cooling a defined space in which the moisture laden but cooled air into which moisture is evaporated is discharged into the space rather than to the exterior of the space.

United States Patent 1 Morse et a1.

[[ EVAPORATIVE COOLERS [75] inventors: Roger Neill Morse, Caulfield;

Donald Pescod, Balwyn; John Joseph Kowalczewski, East Hawthorn, all ofAustralia [73] Assignee: Commonwealth Scientific &

Industrial Research Organization, Campbell, Australia [22] Filed: June1, 1973 [21] Appl. No.1 365,949

[30] Foreign Application Priority Data June 2, 1972 Australia 9205/72[52] U.S. Cl. 261/152; 98/211; 98/17; 165/42; 261/30; 261/D1G. 4 [51]Int. Cl. B01F3/04 [58] Field of Search 261/161, DIG. 4, 30, 152,

[451 July 29,1975

[56] References Cited UNITED STATES PATENTS 1,986,529 1/1935 Ray 261/161X 2,257,639 9/1941 Moore 261/D1G. 4 X 2,587,197 2/1952 Mousel 261/D1G. 4X 2,998,714 9/1961 Bonzer 261/D1G. 4 X 3,606,982 9/1971 Anderson261/D1G. 4 X 3,738,621 6/1973 Anderson 261/D1G. 4 X

Primary Examiner-Frank W. Lutter Assistant Examiner-William Cuchlinski,Jr. Attorney, Agent, or F irm-Sughrue, Rothwell, Mion, Zinn & Macpeak[57] ABSTRACT A method of and installation for evaporatively cooling adefined space in which the moisture laden but cooled air into whichmoisture is evaporated is dis charged into the space rather than to theexterior of the space.

12 Claims, 4 Drawing Figures PATENTEI] JUL 2 9 I975 SHEET N QI PATENTEDJUL29 I975 SHEET EVAPORATIVE COOLERS BACKGROUND OF THE INVENTION Thisinvention relates to cooling installations of the type in which thecooling effect is derived from the evaporation ofa liquid in the path ofan air flow. In particular the invention relates to installations of thetype in which there are two air flows, a primary air flow and asecondary air flow, and in which moisture is evaporated into thesecondary air flow thereby to effect cooling of that flow and by heatexchange of the primary air flow. The required heat exchange occursbetween the primary air and the cooled secondary air and/or between theprimary air and surfaces from which the moisture has been evaporated in,for example, a plate type heat exchanger.

In one previously proposed installation of the abovementioned type, anair flow is drawn from outside a space to be cooled and split intoprimary and secondary flows. The primary air flow is passed through afirst set of air passageways formed in a heat exchanger and dischargedto the interior of the space. The secondary air is passed through asecond set of air passageways in the heat exchanger. It is evaporativelycooled as it passes through the heat exchanger and assists in coolingthe air in the primary air flow. This air stream is then, according tothe prior proposals, discharged outside the space to be cooled.

SUMMARY OF THE INVENTION Although, in the case above described, thesecondary air has been used to cool the primary air, it is stillnevertheless substantially cooler than the outside air. Hitherto it hasbeen regarded as necessary to discharge this air outside the space to becooled because of its high humidity. For example, in a typical case, theoutside air temperature might have a dry bulb temperature of 37C and arelative humidity of about 25%. The secondary air, after evaporativecooling and heat exchange in the heat exchanger with the primary airmight have a dry bulb temperature of 26C but such air, though it iscooler than the outside air, does not provide a comfortable conditionbecause of its high relative humidity, say, 80%. This invention is,however, based on the realization that whilst this moist secondary airflow may not in itself provide a comfortable condition if it is directedat the occupants of the space or is used to provide an overall ambientcondition, it can nevertheless, be used to improve the overall coolingeffect by being discharged to particular areas of the space separatelyfrom the primary air flow. For example, in a vehicle such as amotor-car, bus or truck, use can be made of the relatively lowertemperature of this secondary air to improve the net cooling effectobtained in the passanger cabin by directing it against or along theprincipal heat radiating surfaces of the cabin such as the windscreenand the roof, while the relatively drier and cooler primary air is usedto provide what may be termed jet" cooling of the passengers.

It is therefore a principal object of the invention to provide animproved method of and installation for evaporatively cooling a definedspace.

According to this invention there is provided a method for cooling adefined space, comprising the steps of:

drawing a primary air flow through a first set of pas sageways formed ina heat exchanger and discharging same into the space;

separating a secondary air flow from the primary air flow after it haspassed through the first set of passageways and causing the secondaryair flow to pass through a second set of passageways formed in the heatexchangers and to discharge into the space in a stream which is separatefrom that portion of the primary air flow which is discharged directlyinto the space and,

supplying a predetermined liquid to the secondary air flow within thesecond set of passageways,

whereby the liquid is evaporated within the second set of passageway-sthereby to effect cooling of the secondary air flow and to effectcooling of the primary air flow by heat exchange between the respectivesets of passageways.

The invention also provides an evaporative cooling installationcomprising:

a defined space to be cooled;

a heat exchanger constructed and arranged to define a first set ofpassageways and a second set of passageways in heat exchange relationwith each other;

means to draw a primary air flow through the first set of passagewaysand to discharge the same into the space;

means to cause a secondary air flow to separate from the primary airflow after it has passed through the first set of passageways and tocause the secondary air flow to pass through the second set ofpassageways and to discharge into the space in a stream which isseparate from that portion of the primary air flow which is dischargeddirectly into the space and;

means to supply a predetermined liquid to the secondary air flow withinthe second set of passageways;

whereby the liquid is evaporated within the second set of passageways toeffect cooling of the secondary air flow and to effect cooling of theprimary air flow by heat exchange between the respective sets ofpassageways.

The heat exchanger is preferably a plate type heat exchanger havingspaced apart plates arranged to define the said sets of passageways.

The secondary air flow is preferably separated from the cooled primaryair flow before the primary air flow is discharged into the space. Thisseparation may be so arranged that the secondary air flow enters thesecond set of passageways at the lowest possible wet bulb temperature.

Installations constructed in accordance with the above principles areparticularly useful in providing personal cooling, since the relativelydry and cool primary air flow can be so directed as to provide animmediate cooling effect for the occupants of the space, whereas therelatively moister and warmer secondary air flow can be used to coolheat radiating surfaces exposed to the interior of the space. In, forexample, a vehicle installation, the secondary air flow shouldpreferably be discharged to the upper part of the vehicle cabin to coolthe windscreen and roof of the cabin thereby reducing the amount of heatradiated from these surfaces to the occupants of the vehicle.

The principles of this invention can also be advantageously used toprovide an improved cooling effect in a room, particularly where thereare large heat radiating surfaces such as extensive glass window areas.In this latter case, the primary air flow would be directed into thespace whilst the secondary air flow would be directed over the principalheat radiating window surfaces.

In order that the invention may be better understood examples of itsapplication to a car cooler, to a personal cooler and to a room, willnow be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic sectionalside elevation through a cooler as fitted to a motor car, mounted underthe dashboard.

FIG. 2 is a diagrammatic sectional side elevation through a cooler ofcompact design to provide personal jet" cooling within a room.

FIG. 3 is a side elevation ofa larger installation in, for example aroom, in which the primary air flow is directed inwardly of the spacewhilst the secondary air flow is directed over the principal heatradiating surfaces.

FIG. 4 is a portion of a psychometric chart for a cooler according tothe arrangement shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates theapplication of the invention to a motor car using, so far as possible,the existing heater installation as part of the cooling apparatus. Inview of this, the installation can, when modified in accordance with theinvention, serve a dual purpose as either a cooler or a heater. In thearrangement shown, outside air is taken in through transverse bonnetgrating 4 past heater coil 5, which is inoperative when the installationis functioning as a cooler, by means of a fan 6 as in the existingheater arrangement of the vehicle. This air forms a primary air flow 7at one inlet of a parallel plate type heat exchanger 3 constructed toprovide alternating primary and secondary air passageways, the primaryair passageways being arranged to be transverse to the secondary airpassageways. The air flow passes through the primary air passageways, asindicated by the arrow A in FIG. 1, where it is cooled in a mannerhereinafter described and, on leaving these passageways, is directedupwardly through a duct 14. Fromthis duct, a portion P of the cooled airflow is discharged via flexible conduits 17 through register outlets 1to the interior of the car to provide jet cooling for the front seatpassengers. The register outlets are those which normally serve toprovide flow-through ventilation of the car interior.

The remaining part of the original primary air flow becomes a secondaryair flow 9. The secondary air flow is subsequently directed downwardlythrough the secondary air passageways, as indicated by the arrow B,water or other liquid being provided by sprays 2 for evaporative coolingof the air flow within the secondary air passageways. Heat necessary tofacilitate evaporation of the liquid is derived partly from thesecondary air flow itself and partly through transfer of heat throughthe heat exchanger plates from the primary air flow.

The secondary air flow leaves the heat exchanger at its lower end, isturned upwardly through a duct disposed adjacent and generally parallelto the duct 14 and discharged (arrow S) through a register outlet 13located in the dashboard of the vehicle to provide general cooling ofthe windscreen and roof which normally contribute a substantial part ofthe heat radiated to the vehicle passengers. Water or other liquid whichhas not been evaporated within the secondary air passages drains undergravity and flows through holes at 16 into a water tank 10 from where itflows via tubing 19 to a sump 18. Water or other liquid for the sprays 2is circulated from sump 18 by means of a pump (not shown).

It will be observed that although two separate air flows are createdonly one fan is needed with the arrangement shown. It will also beappreciated that when the car is moving this movement itself willcontribute substantially to the flow of air through the apparatus.

It will also be observed that the secondary air flow passes downwardlythrough the heat exchanger rather than upwardly. Although this serves toappreciably increase the total flow path length, it has been found thatan upwardly moving secondary air flow tends to carry a considerableproportion of the water or liquid droplets sprayed at 2 through register13 onto the windscreen of the vehicle. Thus it is preferred, in order tominimize water or liquid loss, to so arrange the installation that thesecondary air flow passes downwardly through the heat exchanger.

It will be appreciated that the installation illustrated in FIG. 1 neednot be located forwardly of the passenger compartment. It may indeed bedesirable, on converting existing vehicles to incorporate theinstallation, that at least part of the installation be located in theboot of the vehicle.

The personal cooler shown in FIG. 2 can be similar in basic structure toknown personal coolers and can be either portable or fixed in a locationsuch as near a window or a wall. In this arrangement air 23 to be cooledis drawn in at 24 by a fan 25 and cooled as it passes through theprimary air passageways of a plate type heat exchanger 26, as indicatedby arrow A. A portion P of this primary air flow is discharged at anoutlet 27 to provide jet" cooling for the person using the cooler. Theremaining portion of the primary air flow becomes a secondary air flow28, and flows downwardly through the secondary air passageways (arrow B)where it is evaporatively cooled by water or liquid provided by sprays29. Liquid not evaporated within the secondary air passages drains intoa tank 30 from where it is recirculated by a pump 31 which suppliesliquid to the sprays 29. The cooled and moist secondary air is turnedupwardly through a duct 33 past the heat exchanger and discharged (arrowS) at outlet 32 in a direction upwardly and away from the body of theperson using the cooler.

The primary air to be cooled may be drawn from outside the space to beconditioned or from within that space.

In the larger scale installation shown in FIG. 3 a room 40 to be cooledmay typically have a large window 41 in an outwardly facing wall 42. Thecooler 43 is installed in the lower part of the wall, and may be of thesame general type as that shown in FIG. 2. Outside air is drawn into thecooler at 24 and forms the primary air flow as previously described. Aportion of the primary air is discharged inwardly to the room throughthe register 27 and the secondary air S is discharged upwardly over theinterior surface of the window 41 thereby cooling that surface andreducing the amount of heat radiated by it to the interior of the room.

The psychometric chart of FIG. 4 depicts the condition of the air atvarious stages in the cycle of operation of the car cooler of FIG. 1.

Primary air enters the heat exchanger at condition A (a typical summeroutdoor condition). The primary air is cooled to condition B withoutincrease in moisture content and a fraction of this air is discharged tothe car interior to provide jet cooling as shown in FIG. 1. Theremaining fraction of the primary air at condition B then becomes thesecondary air, enters the heat exchanger and is discharged throughregister outlet 13 at condition C. The process from B to C involves thesimultaneous evaporative cooling of the secondary air and the heating ofit by means of heat transferred from the primary air flow. Similar chartchanges can be plotted for the conditions at the various points in FIGS.2 and 3. Thus in FIG. 3 condition B represents the condition of thelaterally discharged air stream P and condition C represents thecondition of the secondary air stream S which is discharged over thewindow surface.

There has been described above three constructions and applicationsaccording to this invention. It will be understood, however, that otherconstructions and applications may be made without departing from thespirit and scope of the invention.

We claim:

1. A method for cooling a defined space, comprising the steps of:

drawing a primary air flow through a first set of passageways formed ina heat exchanger and discharging same into the space;

separating a secondary air flow from the primary air flow after it haspassed through the first set of passageways and causing the secondaryair flow to pass through a second set of passageways formed in the heatexchanger and to discharge into the space in a stream which is separatefrom that portion of the primary air flow which is discharged directlyinto the space and,

supplying a liquid to the secondary air flow within the second set ofpassageways,

whereby the liquid is evaporated within the second set of passagewaysthereby to effect cooling of the secondary air flow and to effectcooling of the primary air flow by heat exchange between the respectivesets of passageways,

said secondary air flow being so discharged into the space as to bedirected onto or along a surface therein which radiates heat into thespace whereby to effect cooling of the surface.

2. The method according to claim 1 wherein the primary air flow isdischarged into a zone of the space which is occupied or to be occupied,whereby to effect cooling of the zone.

3. The method according to claim 1, wherein the secondary flow isseparated from the cooled primary air flow before the primary air flowis discharged into the space.

4. The method according to claim 3, wherein the primary air flow isdischarged into a zone of the space which is occupied or to be occupied,whereby to effect cooling of the zone.

temperature.

6. An evaporative cooling installation comprising:

a defined space to be cooled;

a heat exchanger constructed and arranged to define a first set ofpassageways and a second set of passageways in heat exchange relationwith each other;

means to draw a primary air flow through the first set of passagewaysand to discharge the same into the space;

means to cause a secondary air flow to separate from the primary airflow after it has passed through the first set of passageways and tocause the secondary air flow to pass through the second set ofpassageways and to discharge into the space in s stream which isseparate from that portion of the primary air flow which is dischargeddirectly into the space, means to direct said secondary air flow onto oralong a surface therein which radiates heat into the space whereby toeffect cooling of the surface and;

means to supply a liquid to the secondary air flow within the second setof passageways;

whereby the liquid is evaporated within the second set of passageways toeffect cooling of the secondary air flow and to effect cooling of theprimary air flow by heat exchange between the respective sets ofpassageways.

7. The installation according to claim 6 and further comprising means todirect said primary air flow into a zone of the space which is occupiedor to be occupied, whereby to effect cooling of the zone.

8. The installation according to claim 6, wherein the heat exchanger isa plate type heat exchanger having spaced apart plates arranged todefine the said sets of passageways.

9. The installation according to claim 6, wherein the means to cause thesecondary air flow to separate from the primary air flow is such thatthe secondary air flow separates from the primary air flow before theprimary air flow is discharged to the space.

10. The installation according to claim 9, wherein the primary air flowis discharged into a zone of the space which is occupied or to beoccupied, whereby to effect cooling of the zone.

11. The installation according to claim 9, wherein the means to causethe secondary air flow to separate from the primary air flow is suchthat the secondary flow enters the secondary set of passageways at thelowest possible wet bulb temperature.

12. A vehicle comprising:

a passenger cabin;

a heat exchanger arranged to define a first set of passageways and asecond set of passageways in heat exchange relation with each other;

means to draw a primary air flow from the exterior of the vehiclethrough the first set of passageways and to discharge the same into azone of the cabin which is occupied or to be occupied;

means to cause a secondary air flow to separate from the primary airflow after it has passed through the first set of passageways but beforeit has been discharged into the cabin, and to cause the secondary airflow to pass through the second set of passageway and to discharge intothe cabin in a stream which is separate from that portion of the primaryair flow which is discharged directly into the space 5 and which streamis directed onto or along the interior surface of the vehicle windscreenand/or cabin roof; and

3,897,526 7 8 means to supply a liquid to the secondary air flow daryair flow and to effect cooling of the primary within the second set ofpassageways; air flow by heat exchange between the respective wherebythe liquid is evaporated within the second set of passageways. set ofpassageways to effect cooling of the secon-

1. A METHOD FOR COOLING A DEFINED SPACE, COMPRISING THE STEPS OF: DRAWING A PRIMARY AIR FLOW THROUGH A FIRST SET OF PASSAGEWAYS FOMED IN A HEAT EXCHANGER AND DISCHARGING SAME INTO THE SPACE, SEPARATING A SECONDARY AIR FLOW FROM THE PRIMARY AIR FLOW AFTER IT HAS PASSED THROUGH THE FIRST SET OF PASSAGEWAYS AND CAUSING THE SECONDARY AIR FLOW TO PASS THROUGH A SECOND SET OF PASSAGEWAYS FORMED IN THE HEAT EXCHANGER AND TO DISCHARGE INTO THE SPACE IN A STREAM WHICH IS SEPARATE FROM THAT PORTION OF THE PRIMARY AIR FLOW WHICH IS DISCHARGED DIRECTLY INTO THE SPACE AND, SUPPLYING A LIQUID TO THE SECONDARY AIR FLOW WITHIN THE SECOND SET OF PASSAGEWAYS, WHEREBY THE LIQUID IS EVAPORATED WITHIN THE SECOND SET OF PASSAGEWAYS THEREBY TO EFFECT COOLING OF THE SECONDARY AIR FLOW AND TO EFFECT COOLING OF THE PRIMARY AIR FLOW BY HEAT EXCHANGE BETWEEN THE RESPECTIVE SETS OF PASSAGEWAYS, SAID SECONDARY AIR FLOW BEING SO DISCHARGED INTO THE SPACE AS TO BE DIRECTED ONTO OR ALONG A SURFACE THEREIN WHICH RADIATES HEAT INTO THE SPACE WHEREBY TO EFFECT COOLING OF THE SURFACE.
 2. The method according to claim 1 wherein the primary air flow is discharged into a zone of the space which is occupied or to be occupied, whereby to effect cooling of the zone.
 3. The method according to claim 1, wherein the secondary flow is separated from the cooled primary air flow before the primary air flow is discharged into the space.
 4. The method according to claim 3, wherein the primary air flow is discharged into a zone of the space which is occupied or to be occupied, whereby to effect cooling of the zone.
 5. The method according to claim 3, wherein the secondary air flow is separated such that it enters the second set of passageways at the lowest possible wet bulb temperature.
 6. AN EVAPORATIVE COOLING INSTALLATION COMPRISING: A DEFINED SPACE TO BE COOLED, A HEAT EXCHANGER CONSTRUCTED AND ARRANGED TO DEFINE A FIRST SET OF PASSAGEWAYS AND A SECOND SET OF PASSAGEWAYS IN HEAT EXCHANGE RELATION WITH EACH OTHER, MEANS TO DRAW A PRIMARY AIR FLOW THROUGH THE FIRST SET OF PASSAGEWAYS AND TO DISCHARGE THE SAME INTO THE SPACE, MEANS TO CAUSE A SECONDARY AIR FLOW TO SEPARATE FROM THE PRIMARY AIR FLOW AFTER IT HAS PASSED THROUGH THE FIRST SET OF PASSAGEWAYS AND TO CAUSE THE SECONDARY AIR FLOW TO PASS THROUGH THE SECOND SET OF PASSAGEWAYS AND TO DISCHARGE INTO THE SPACE IN S STREAM WHICH IS SEPARATED FROM THAT PORTION OF THE PRIMARY AIR FLOW WHICH IS DISCHARGED DIRECTLY INTO THE SPACE, MEANS TO DIRECT SAID SECONDARY AIR FLOW ONTO OR ALONG A SURFACE THEREIN WHICH REDIATES HEAT INTO THE SPACE WHEREBY TO EFFECT COOLING OF THE SRFACE AND, MEANS TO SUPPLY A LIQUID TO THE SECONDARY AIR FLOW WITHIN THE SECOND SET OF PASSAGEWAYS, WHEREBY THE LIQUID IS EVAPORATED WITHIN THE SECOND SET OF PASSAGEWAYS TO FFECT COOLING OF THE SECONDARY AIR FLOW AND TO EFFECT COOLING OF THE PRIMARY AIR FLOW BY HEAT EXCHANGE BETWEEN THE RESPECTIVE SETS OF PASSAGEWAYS.
 7. The installation according to claim 6 and further comprising means to direct said primary air flow into a zone of the space which is occupied or to be occupied, whereby to effect cooling of the zone.
 8. The installation according to claim 6, wherein the heat exchanger is a plate type heat exchanger having spaced apart plates arranged to define the said sets of passageways.
 9. The installation according to claim 6, wherein the means to cause the secondary air flow to separate from the primary air flow is such that the secondary air flow separates from the primary air flow before the primary air flow is discharged to the space.
 10. The installation according to claim 9, wherein the primary air flow is discharged into a zone of the space which is occupied or to be occupied, whereby to effect cooling of the zone.
 11. The installation according to claim 9, wherein the means to cause the secondary air flow to separate from the primary air flow is such that the secondary flow enters the secondary set of passageways at the lowest possible wet bulb temperature.
 12. A vehicle comprising: a passenger cabin; a heat exchanger arranged to define a first set of passageways and a second set of passageways in heat exchange relation with each other; means to draw a primary air flow from the exterior of the vehicle through the first set of passaGeways and to discharge the same into a zone of the cabin which is occupied or to be occupied; means to cause a secondary air flow to separate from the primary air flow after it has passed through the first set of passageways but before it has been discharged into the cabin, and to cause the secondary air flow to pass through the second set of passageway and to discharge into the cabin in a stream which is separate from that portion of the primary air flow which is discharged directly into the space and which stream is directed onto or along the interior surface of the vehicle windscreen and/or cabin roof; and means to supply a liquid to the secondary air flow within the second set of passageways; whereby the liquid is evaporated within the second set of passageways to effect cooling of the secondary air flow and to effect cooling of the primary air flow by heat exchange between the respective set of passageways. 